Section 55. When necessary to call out any part of the unorganized militia for duty, the commander-in-chief shall issue a proclamation directed to the mayors or city managers and selectmen, who shall forthwith, by written order or oral notice to each individual, or by proclamation on their part, appoint a time and place for the assembling of the unorganized militia in their respective cities and towns, and shall then and there draft as many thereof, or accept as many volunteers, as are required by the order of the commander-in-chief, and shall forthwith forward to him a list of the persons so drafted or accepted as volunteers.